29CFR4.4.187 - Recovery of underpayments.

So much of the accrued payments due either on the contract or on any other contract (whether subject to the Service Contract Act or not) between the same contractor and the Government may be withheld in a deposit fund as is necessary to pay the employees.

http://www.dol.gov/dol/allcfr/ESA/Title_29/Part_4/29CFR4.187.htm